This application requests support to continue the program of psychobiological research in the Department of Psychiatry, Emory University School of Medicine. The School of Medicine together with the Georgia Mental Health Institute wish to support a comprehensive research program that is basic to problems of brain function, behavior and mental health. The aim is to investigate the physiological and, in particular, the neuroendocrine basis of patterns of primate behavior. Emphasis is placed on patterns of instinctive and of emotional behavior, on the affectional and sexual responses, and also on the agonistic and aggressive responses. Central to this program is the accurate quantification of primate behavior using ethological techniques both in the dyadic situation and in the social group. We are concerned with understanding the physiological mechanisms that determine an animal's motivational state in terms of the underlying brain mechanisms involved. This necessitates utilization of brain implantation techniques with steroid hormones, operant conditioning techniques, and the radioimmunoassay of plasma steroids; emphasis is placed on a multidisciplinary approach. Detailed attention will be given to the mechanisms by which information concerning an animal's motivational state is communicated to conspecifics, and this necessitates an understanding of the informational content of behavioral displays, and also of the chemical communication signaling systems involved.